Detection and treatment of primary and metastatic tumors, particularly in early stage cancer, continues to be a significant challenge. The technical objective of this SBIR is to demonstrate that substantial improvements to image-guided needle-based interventions used in cancer detection and treatment can be realized by providing accurate easy-to-use guidance directly integrated into an ultrasound probe. Using a novel configuration of integrated cameras and projection, guidance will be achieve by fusing real-time surface information and real-time needle tracking with preoperative imaging. The resulting system is compact, cost-effective, and flexible. This SBIR Phase II project will develop the software tools that realize these capabilities, and will validate the overall system in animal and human trials. The software tools to be developed include: 1) surface reconstruction using real-time structured-light stereo, and 2) surface registration and needle tracking algorithms that are compatible with ultrasound-guided biopsy; 3) information fusion to integrate pre-operative CT or MRI with ultrasound and video imaging; 4) unique and accurate guidance methods require almost no change to standard clinical workflow. Algorithm performance will be demonstrated on animal models, and on human subjects during biopsy. Measurable endpoints will include the time to perform a biopsy, overall navigation accuracy, and target registration error.